12 Inflammatory Conditions That Show Up on the Skin First

6. Vasculitis - When Blood Vessels Under Siege Signal Through Skin

Vasculitis encompasses a group of inflammatory conditions affecting blood vessels of various sizes, and cutaneous manifestations often serve as the most visible and accessible indicators of this potentially serious systemic process. The skin's rich vascular network makes it particularly susceptible to vasculitic changes, with dermatological findings frequently being the presenting feature that leads to diagnosis. Small vessel vasculitis, such as hypersensitivity vasculitis or leukocytoclastic vasculitis, typically presents as palpable purpura—raised, purple lesions that do not blanch with pressure—most commonly appearing on the lower extremities due to gravitational effects on blood flow. Medium-sized vessel vasculitis, including polyarteritis nodosa, may present with livedo reticularis, subcutaneous nodules, or ulcerations, while large vessel involvement can cause claudication symptoms and asymmetric pulse findings. The pathophysiology involves immune complex deposition, direct antibody attack against vessel walls, or cell-mediated immune responses targeting vascular structures, leading to inflammation, necrosis, and potential organ dysfunction. Cutaneous vasculitis can be primary (isolated to the skin) or secondary to systemic conditions such as systemic lupus erythematosus, rheumatoid arthritis, or infections. The morphology, distribution, and associated symptoms of skin lesions provide crucial diagnostic clues about the underlying type of vasculitis, the size of vessels involved, and the urgency of systemic evaluation and treatment required to prevent serious complications.